Belinda Bencic was responsible for eliminating Venus Williams on Monday. Photo: Julian Smith/BackpagePix

MELBOURNE – Seed slayers Belinda Bencic and Zhang Shuai were brought back down to earth at the Australian Open on Wednesday as they both failed to follow up their first-round exploits.

Swiss Bencic, who knocked out last year's runner-up Venus Williams on a day of shocks on Monday, slumped to a 6-1 6-3 defeat by Thai qualifier Luksika Kumkhum.

Zhang, conquerer of U.S. Open champion Sloane Stephens in round one, was also toppled by a qualifier in the shape of Czech Republic's Denisa Allertova. Allertova won 6-4 7-6(5).

With 15-year-old Ukrainian Marta Kostyuk also getting through it means three qualifiers have made the third round in the bottom half of the wide open women's draw.

Timea Babos, who put paid to the hopes of a third American seed, CoCo Vandeweghe, in the first round was in action later.

Luksika, ranked 124th in the world, produced a masterful display to beat the former world number seven Bencic and reach the third round of a major for the first time having twice reached the second round of the Australian Open.